CODEWITHSUNDEEP
pythonpython-3.x
jayko03
jayko03

Reputation: 2481

Does python operator not need condition statement?

I saw the code snippet that I think it is illegal, but not sure yet.

This is not exactly the same code, but I try to keep the original as much as I can.

def validate_check(string):
    try:
        len(string) > 0
        # do something
    except Error:
        # do something

Doesn't len(string) > 0 have to be in condition statement? Or is it something python syntax?

Upvotes: 0

Views: 59

Answers (3)

M. Bauer
M. Bauer

Reputation: 199

If string is None, the len function will raise an error.

Perhaps it's the reason why your function is named validate_check.

Upvotes: 1

jedwards
jedwards

Reputation: 30240

Doesn't len(string) > 0 have to be in condition statement?

No, but the example you've provided doesn't make a ton of sense.

Here's a different, similar construction that might help:

x = input()

try:
    10 / int(x)
except ZeroDivisionError:
    print("Can't divide by zero")
except ValueError:
    print("Can't convert to int")

The result of 10 / int(x) is calculated (to see whether it will raise an error), but the result of that calculation is thrown away.

The reason I say your example is a bit weird is because the comparison with zero will have no effect whatsoever. So while the code will serve as a way of testing whether len can be called on string, that's about all it'll do.

Upvotes: 4

L3viathan
L3viathan

Reputation: 27323

This is valid syntax. But if you write:

len(string) > 0
print("hi")

then "hi" will be printed regardless of the length of the string. The only relevance this statement has is that it will throw an exception when either string has no length, or the result of len(string) is not comparable to 0.

What the author of the code is doing is avoiding the more complicated check if isinstance(string, str) and string: (or, I guess, if isinstance(string, collections.abc.Sized) and len(string) > 0).

Upvotes: 1

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